Hiroyoshi Ueda

Piezoelectricity in three‐phase systems: Effect of the boundary phase

The influence of electrical conductivity on the piezoelectricity of polymers was studied using a three‐phase model. The model consists of a continuous nonpiezoelectric phase (phase 1) surrounding a spherical piezoelectric phase (phase 2), which is itself bounded by an electrically conductive shell (phase 3). The piezoelectric constants for the system can be expressed as d=d2KPKT and e=e2KPKS, where d2 and e2 are the piezoelectric strain and stress constants of phase 2, respectively, and KP is a function of the dielectric constants of phases 1, 2, and 3. KT and KS are expressed as functions of the elastic constant of each phase. The piezoelectric constants d and e decrease with decreasing elastic constant of phase 3 and with increasing dielectric constant of phase 3. The three‐phase system shows a Maxwell–Wagner piezoelectric relaxation with a relaxation time given by τ=(2e1+e2+ηe3)/(2σ1+σ2+ησ3), where η=2δ/a. In these expressions ei and σi are the dielectric constant and the electrical conductivity of pha...

CRITICAL MISCIBILITY PHENOMENA IN BLENDS OF CHLORINATED POLYETHEYLENES

Binary blends of chlorinated polyethylenes (CPEs) (37 to 69 wt% Cl) were studied by measuring the Tg behavior. At a given temperature the miscibility of the blends was principally dependent on the difference in chlorine content between the two component CPEs and also on the mean degree of chlorination. The miscibility of these systems at 150 o C was maximal around an average mole fraction chlorination, β, of 0.5. At a given β, the consolute points converged as the difference in chlorine content of the blend constituents increased

Shear piezoelectricity in ethylene dichloride solution of poly‐γ‐methyl‐L‐glutamate

When ultrasonic shearing stress is applied to electrically oriented α‐helical molecules of poly‐γ‐methyl‐L‐glutamate (PMG) in solution, electric potential is observed in the direction perpendicular to the plane of the shear stress. The apparent shear pizeoelectric coefficient is about 1×10−9 V m2/N and five orders of magnitude as small as that for the oriented solid PMG. The effect is not observed for PMG solutions with non‐α‐helical solvents such as dichloroacetic acid, which suggest that the effect is due to shear piezoelectricity in α‐helical polypeptides.

Critical Miscibility Phenomenain Blends of Chlorinated Polyethylenes

Abstract Critical miscibility phenomena in binary blends of chlorinated polyethylenes (CPEs) with a wide range of degree of chlorination (37 to 69 wt 970 CI) were studied by measuring the glass transition behavior. At a given temperature the miscibility of the blends was principally dependent on the difference in chlorine content between the two component CPEs and also on the mean degree of chlorination. The miscibility of these systems at 150°C was maximal around an average mole fraction chlorination, β, of 0.5. The systems displayed upper critical solution temperatures when β was below 0.5, while lower critical solution temperatures were observed when β | was above 0.5. At a given β, | the consolute points converged as the difference in chlorine content of the blend constituents increased. It appears that this double consolute point temperature decreases with increasing average degree of chlorination. A more refined analysis, taking into account the possible presence of CCl2 units and the microstructure...